1. Field of the Invention
This invention relates to energy generation devices, such as a time delay fuse, and more particularly to a device or fuse of that kind made from a piezoelectric polymer film.
In a time-delayed energy system functioning as a fuse in a projectile, it is desired that mechanical energy derived from the initial firing of the projectile be converted to electrical energy and stored with the assistance of a diode for a short period until called upon to energize detonation. A fuse of this kind is required to fit inside a small caliber bullet and remain positioned to energize the so-called secondary detonator situated in the tip of the bullet.
2. Description of the Prior Art
Prior efforts with piezoelectric transducers in fuses for projectiles have been unsuccessful because the transducers have been of the piezoelectric ceramic variety which proved to be fragile and therefore unreliable for ballistic applications.
Piezoelectric polymer transducers are less fragile than piezoelectric ceramic transducers, and they are widely used as transducers. A prior effort was made to use the polymer variety of piezoelectric transducer for a fuse by preparing a stack of thin circular wafers which had been cut from polymer film and provided on opposite sides with respective positive and negative layers. This prior effort failed because it was not possible to establish a reliable electrical connection to all positive layers along one path and a separate reliable connection to all negative layers along another path.
Moreover, a transducer formed by pleating a continuous strip of polymer film having negative and positive layers on its opposite sides often failed at the bends between folds.